Recently, automatic identification systems have been actively introduced for baggage management in airports. In the automatic identification systems, a device incorporating hardware and software automatically performs data reading and data identification with respect to a management target, without human operation. Specifically, some automatic identification systems use RFID (Radio Frequency IDentification) tags. The RFID tag includes a memory for recording identification data, and a coil antenna for data transmission by wireless communication, and its outer surface is printed with letters or barcodes corresponding to e.g. the identification data. Data transmission and printing to the RFID tag is performed by an RFID tag printer, for example.
FIG. 6 illustrates a conventional RFID tag printer (see Patent document 1, for example). The illustrated RFID tag printer X includes a thermal printhead 91 for printing on RFID tags 99, and two coil antennas 93A, 93B each serving as data transmitting and receiving means with respect to the RFID tags 99. The RFID tag printer X operates in the manner described below.
First, an external computer 94 sends identification data corresponding to each of the RFID tags 99 to a controller 96 via a communication I/F 95. Then, a sheet 98 provided with the RFID tags 99 is fed out of an RFID tag sheet roll 97. When each of the RFID tags 99 arrives at a position above the coil antenna 93A as seen in the figure, the controller 96 issues a command to cause the coil antenna 93A to generate electromagnetic field. When an antenna coil (not shown) of the RFID tag 99 is brought into the electromagnetic field, electrical power supply as well as transmission of identification data to be recorded are simultaneously performed to the RFID tag 99 by electromagnetic induction. In this way, corresponding identification data is recorded in the memory (not shown) of each RFID tag 99. Next, when the RFID tag 99 arrives at a position below the thermal printhead 91, the RFID tag 99 is held between the thermal printhead 91 and a platen roller 92. In this state, letters, marks, and barcodes corresponding to the identification data are printed on the RFID tag 99. When the RFID tag 99 arrives at a position above the antenna coil 93B, the identification data recorded in the memory (not shown) of the RFID tag 99 is sent to the controller 96 via the antenna coil 93B, utilizing electromagnetic induction. Then, the controller 96 checks the validity of the identification data recorded in the RFID tag 99. In this way, the RFID tag printer X performs printing and data transmission relative to the RFID tag 99.
However, such RFID tag printer X has problems as described below.
Firstly, in the RFID tag printer X, the thermal printhead 91 and the antenna coils 93A, 93B are arranged in series in the feeding direction of the RFID tag 99. In order to prevent the antenna coils 93A, 93B and the platen roller 92 from interfering with each other, the thermal printhead 91 needs to be spaced from the antenna coils 93A, 93B. Thus, the thermal printhead 91 and the antenna coils 93A, 93B need a large space for installation, which prevents downsizing of the RFID tag printer X.
Secondly, the intensity of the electromagnetic field generated by the antennal coils 93A, 93B becomes weaker as proceeding further from the antenna coils 93A, 93B. In order to properly perform data transmission with the RFID tag 99, the RFID tag 99 is required to pass through an area in the electromagnetic field having the minimum operating magnetic intensity. By performing data transmission within an area with high magnetic intensity, reliable and high-speed data transmission is performed. Thus, it is preferable that the antenna coils 93A, 93B are positioned as close to the RFID tag 99 as possible. However, the RFID tag printer X has room for improvement in positioning the antenna coils 93A, 93B closer to the RFID tag 99 without contacting each other.
Patent Document: JP-A-2003-132330